| Rockville to Reading (Pennsylvania) | 108.64 mi (174.83 km) |
| Rockville to Red Bank (New Jersey) | 185.92 mi (299.21 km) |
| Rockville to Red Bank (Tennessee) | 525.59 mi (845.85 km) |
| Rockville to Red Bluff (California) | 2,374.31 mi (3,821.08 km) |
| Rockville to Red Hill (South Carolina) | 380.80 mi (612.84 km) |
| Rockville to Red Oak (Texas) | 1,186.72 mi (1,909.84 km) |
| Rockville to Red Wing (Minnesota) | 879.46 mi (1,415.36 km) |
| Rockville to Redan (Georgia) | 536.54 mi (863.47 km) |
| Rockville to Redding (California) | 2,374.56 mi (3,821.48 km) |
| Rockville to Redland (Maryland) | 3.52 mi (5.67 km) |
| Rockville to Redlands (California) | 2,229.46 mi (3,587.97 km) |
| Rockville to Redmond (Oregon) | 2,272.40 mi (3,657.08 km) |
| Rockville to Redmond (Washington) | 2,299.84 mi (3,701.23 km) |
| Rockville to Redondo Beach (California) | 2,298.74 mi (3,699.47 km) |
| Rockville to Redwood City (California) | 2,421.23 mi (3,896.59 km) |
